This invention relates to a device for calculating the ratio by which a selected part of a given piece of artwork is to be reduced or enlarged in reproducing it so that the reproduction will just fit in a space set aside for that purpose on a page. In particular, the device analyzes the proportion of the size of the selected part, compares it with the size of the space set aside, and gives a numerical readout of the proportion, or magnification ratio, between the two size values.
Printed pages frequently include such artwork as photos, drawings, and graphs alongside or embedded in related textual material printed in columns separated by narrow blank areas. The artwork area can be of any size but is frequently related to the column width. Instead of simply arranging to print the artwork in the same size space as the original artwork, the person laying out the page usually has to measure the original artwork, or the portion to be reproduced, and calculate the optical enlargement or reduction necessary to make the reproduction fit properly in the selected space. The selected portion is marked to indicate its boundaries, and the marked artwork, together with the enlargement or reduction ratio, is given to the person responsible for making the photographic reproduction thereof to be used in the printing process.
Instead of using the entire phrase "enlargement or reduction" hereinafter, the word "magnification" will be used, with the understanding that magnification greater than unity is enlargement and magnification less than unity is reduction. The magnification is represented by a number determined by the ratio of the area covered by the reproduced part of the artwork to the area of that part of the original artwork, and when the artwork, marked to indicate the desired part, is given, along with the magnification value, to someone responsible for making the reproduction, it is a straightforward matter to make the reproduction for inclusion in the final layout.
A further thing must be understood. While the same magnification will be applied to both the horizontal and vertical dimensions of that part of the artwork to be reproduced, the selection of the magnification value is based on only one of those dimensions, usually the horizontal dimension. Different magnification values for the two dimensions is almost never permissible, and the person making the layout must keep that in mind in allocating space on the page and in marking the part of the initial artwork to be reproduced. Some accommodation may be made by cropping the final reproduction differently than may have originally been planned.
The procedure commonly used up to now in determining the magnification value has been for the person making the layout to mark the initial artwork to indicate at least the corners of the portion to be reproduced. Then, a dimension, usually the width, of that portion is measured and the number representing that value is divided into the same dimension of the space into whloh the reproduction of that portion of the artwork is to fit. The quotient obtained by that division is given to the person who is to make the reproduction, and that quotient is then applied as the magnification value in reproducing the portion of the initial artwork marked by the layout person.
Since the measurement of the selected portion of the original artwork is made with one instrument, usually a ruler, and the calculation of the magnification value is done separately, either as a partly or wholly mental operation or by means of a slide rule or calculator, it is entirely possible for an error to creep into the calculation, either by entering a wrong number or, particularly if the magnification value is computed mentally, by making a mistake in the mathematical operation.